Re: [PATCH v3] uprobes: turn trace_uprobe's nhit counter to be per-CPU one

2024-08-29 Thread Andrii Nakryiko
On Tue, Aug 27, 2024 at 8:55 PM Masami Hiramatsu wrote: > > On Tue, 13 Aug 2024 13:34:09 -0700 > Andrii Nakryiko wrote: > > > trace_uprobe->nhit counter is not incremented atomically, so its value > > is questionable in when uprobe is hit on multiple CPUs simultaneously. > > > > Also, doing this

Re: [PATCH v3] uprobes: turn trace_uprobe's nhit counter to be per-CPU one

2024-08-27 Thread Google
On Tue, 13 Aug 2024 13:34:09 -0700 Andrii Nakryiko wrote: > trace_uprobe->nhit counter is not incremented atomically, so its value > is questionable in when uprobe is hit on multiple CPUs simultaneously. > > Also, doing this shared counter increment across many CPUs causes heavy > cache line bou

Re: [PATCH v3] uprobes: turn trace_uprobe's nhit counter to be per-CPU one

2024-08-27 Thread Google
On Tue, 13 Aug 2024 13:34:09 -0700 Andrii Nakryiko wrote: > trace_uprobe->nhit counter is not incremented atomically, so its value > is questionable in when uprobe is hit on multiple CPUs simultaneously. > > Also, doing this shared counter increment across many CPUs causes heavy > cache line bou

Re: [PATCH v3] uprobes: turn trace_uprobe's nhit counter to be per-CPU one

2024-08-26 Thread Jiri Olsa
On Tue, Aug 13, 2024 at 01:34:09PM -0700, Andrii Nakryiko wrote: > trace_uprobe->nhit counter is not incremented atomically, so its value > is questionable in when uprobe is hit on multiple CPUs simultaneously. > > Also, doing this shared counter increment across many CPUs causes heavy > cache lin

Re: [PATCH v3] uprobes: turn trace_uprobe's nhit counter to be per-CPU one

2024-08-21 Thread Andrii Nakryiko
On Tue, Aug 13, 2024 at 1:34 PM Andrii Nakryiko wrote: > > trace_uprobe->nhit counter is not incremented atomically, so its value > is questionable in when uprobe is hit on multiple CPUs simultaneously. > > Also, doing this shared counter increment across many CPUs causes heavy > cache line bounci

[PATCH v3] uprobes: turn trace_uprobe's nhit counter to be per-CPU one

2024-08-13 Thread Andrii Nakryiko
trace_uprobe->nhit counter is not incremented atomically, so its value is questionable in when uprobe is hit on multiple CPUs simultaneously. Also, doing this shared counter increment across many CPUs causes heavy cache line bouncing, limiting uprobe/uretprobe performance scaling with number of CP